The present invention relates to heat-relaxable substrates. More particularly, the present invention provides high density arrays on heat-relaxable substrates, along with methods and apparatus for relaxing substrates using electromagnetic energy.
Arrays may be used in a variety of applications, such as gene sequencing, monitoring gene expression, gene mapping, bacterial identification, drug discovery, and combinatorial chemistry. Many of these applications involve expensive and oftentimes difficult to obtain samples and reagents. Accordingly, high density arrays are desirable because the use of such arrays may dramatically increase efficiency with respect to limited or expensive samples when compared to standard arrays, such as a 96 well plate. For example, a 96 well plate may require several hundred microliters of sample per well to run a diagnostic experiment whereas a high-density array would require only a fraction of that sample for the entire array. In addition to the reduction of volume, miniaturization allows hundreds or thousands of tests to be performed simultaneously. Furthermore, a high-density array may be more versatile than a standard array because of the wide variation of chemistries that may be present on a single array.
Problems in the manufacturing of high-density arrays on standard substrates, e.g., glass microscope slides, include the need for multiple steps to produce the arrays with densely packed reactants. The manufacture of high-density arrays is further complicated when different chemistries are required at different binding sites on the arrays, such as required for manufacturing nucleic acid arrays.
Attempts to address the need for high-density arrays have included using oriented polymeric films in place of glass slides as the substrate for the arrays. The arrays can include binding sites formed on the oriented polymeric films in a larger format that is easier to manufacture, after which the oriented polymeric films can be relaxed by applying thermal energy to the substrate to provide arrays with high-density sites. Examples of such arrays are described in WO 99/53319 (HIGH DENSITY, MINIATURIZED ARRAYS AND METHODS OF MANUFACTURING SAME, published Oct. 21, 1999) and commonly assigned U.S. patent application Ser. No. 09/287,379, filed Apr. 7, 1999, entitled HIGH DENSITY, MINIATURIZED ARRAYS AND METHODS OF MANUFACTURING SAME.
Although the oriented polymeric films provide significant advantages in array manufacturing, their use does pose additional problems during the substrate relaxation process. One potential problem is achieving uniform transmission of thermal energy to the array substrate. Another potential problem is curling or other distortion of the substrate during the application of thermal energy to induce relaxation.
Oriented polymeric films used in, e.g., packaging applications, are typically relaxed using thermal energy supplied by air. When used as packaging, however, the flatness of the film after relaxation is typically not important because the film is constrained around a package, typically conforming to the shape of the package. In applications where a flat film is desired after relaxation, the film is typically placed in tension. An example of one such application is in the use of oriented polymeric films over windows to prevent drafts, provide additional insulation, etc. When used on windows, the film is held in tension between, e.g., adhesive tapes applied to the window frame. When provided as the substrate of an array, however, the film is not so constrained or tensioned, thereby causing the potential for curling as described above.
Another issue to address is how to quickly and efficiently supply the thermal energy required to relax the film. The use of conductive heating devices, e.g., hot plates, may require the constant attention of an operator or feedback control systems to prevent overheating and/or uneven heating of the film.
Another concern with heat-relaxable arrays manufactured with attached or embedded materials that make the array useful for bioanalytical applications, e.g., DNA, RNA, proteins, polysaccharides, antibodies, etc., is that the application of excessive thermal or other forms of energy may adversely affect the functional performance of the materials on the array. invention provides articles, such as high density arrays, including heat-relaxable substrates that can be relaxed by exposure to electromagnetic energy. Methods of relaxing arrays including heat-relaxable substrates and reactants affixed thereto are also provided in connection with the present invention. In still other embodiments, the present invention also provides methods of manufacturing such articles, as well as systems and apparatus for relaxing the same using electromagnetic energy.
In some embodiments, the substrates suitable for use in manufacturing arrays may themselves include electromagnetic energy sensitive Curie point material in their construction, in which case exposure of the substrates to suitable electromagnetic energy can provide the thermal energy required to cause the substrates to relax. The substrates may additionally comprise linking agents or masks, in which case the electromagnetic energy sensitive material may be included in the linking agents or masks. Such methods for providing energy may be referred to as direct heating, i.e., no additional apparatus must be supplied to cause the conversion of electromagnetic energy to heat that is used to relax the substrates.
In preferred embodiments, the substrates include a coating of linking agents, with electromagnetic sensitive material included in the substrate. In a most preferred embodiment, arrays include reactants affixed to the substrates.
Substrates that include an electromagnetic energy sensitive material in their construction may also be placed in a system or apparatus that also includes the same or a different electromagnetic energy sensitive material to provide the thermal energy needed to relax the substrate when exposed to electromagnetic energy.
In its various aspects, the present invention provides a convenient manner of relaxing substrates that include heat-relaxable material. The amount of energy supplied to relax the substrates can be easily controlled and the process can be performed quickly and economically.
In preferred embodiments, wherein reactants are affixed to the substrates, additional benefits may be achieved. For example, after relaxation, the resulting high density arrays can provide a level of flatness useful in activating accurate hybridization results.
In another aspect of the invention, methods are provided for relaxing a substrate. In one embodiment, a method includes providing an array including a heat-relaxable substrate and reactants affixed thereto; providing electromagnetic energy sensitive material
In preferred embodiments, wherein reactants are affixed to the substrates, additional benefits may be achieved. For example, after relaxation, the resulting high density arrays can provide a level of flatness useful in achieving accurate hybridization results.
In another aspect of the invention, methods are provided for relaxing a substrate. In one embodiment, a method includes providing an array including a heat-relaxable substrate and reactants affixed thereto; providing electromagnetic energy sensitive material in proximity to the substrate; and directing electromagnetic energy towards the electromagnetic energy sensitive material, wherein the electromagnetic energy is converted into thermal energy and conducted to the heat-relaxable material, thereby causing the heat-relaxable material in the substrate to relax.
In another aspect, the present invention provides apparatus for relaxing heat-relaxable articles. In one aspect, the present invention includes the apparatus having a first surface; a second surface opposed to and spaced from the first surface; and electromagnetic energy sensitive material in thermal communication with the first surface, whereby heating of the electromagnetic energy sensitive material by electromagnetic energy increases the temperature of the first surface.
These and other features and advantages of the present invention are described in connection with illustrative embodiments of the invention below.
For purposes of this invention, the following definitions shall have the meanings set forth.
xe2x80x9cAffixxe2x80x9d shall include any mode of attaching reactants to a substrate. Such modes shall include, without limitation, covalent and ionic bonding, adherence, such as with an adhesive, and physical entrapment within a substrate. In the case of linking agents, reactants may be affixed to the substrate by linking agents that are created by functionalizing a surface, such as with an acid wash, or by linking agents that are coated on the substrate.
xe2x80x9cAnalytexe2x80x9d shall mean a molecule, compound, composition or complex, either naturally occurring or synthesized, to be detected or measured in or separated from a sample of interest. Analytes include, without limitation, proteins, peptides, amino acids, fatty acids, nucleic acids, carbohydrates, hormones, steroids, lipids, vitamins, bacteria, viruses, pharmaceuticals, and metabolites.
xe2x80x9cBinding sitexe2x80x9d shall mean a discrete location on a substrate wherein reactants are affixed thereto. A single binding site may include a quantity of one or more of the same reactants affixed to the substrate.
xe2x80x9cCurie point materialxe2x80x9d shall mean a magnetic material having a Curie temperature sufficiently high to raise a xe2x80x9cHeat-relaxablexe2x80x9d material to or above its relaxation temperature when exposed to electromagnetic energy
xe2x80x9cElectromagnetic energyxe2x80x9d shall mean energy having rapidly oscillating electric and magnetic components, regardless of wavelength or frequency, that can provide the energy required to relax an array, e.g., microwave energy and radio-frequency (RF) energy.
xe2x80x9cHeat-relaxablexe2x80x9d shall mean, in the context of a material, such as a substrate, that the material undergoes some relaxation in at least one dimension in response to the transmission of thermal energy into the material.
xe2x80x9cLinking agentxe2x80x9d shall mean any chemical species capable of affixing a xe2x80x9cReactantxe2x80x9d to the substrate.
xe2x80x9cMicrowave energyxe2x80x9d shall mean electromagnetic energy having a frequency in the range of from about 108 Hz to about 3xc3x971011 Hz.
xe2x80x9cRadio Frequency (RF) energyxe2x80x9d shall mean electromagnetic energy having a frequency in the range of from about 104 Hz to about 107 Hz.
xe2x80x9cReactantxe2x80x9d shall mean any chemical molecule, compound, composition or complex, either naturally occurring or synthesized, that is capable of binding an analyte in a sample of interest either alone or in conjunction with a molecule or compound that assists in binding the analyte to the substrate, such as, for example, a coenzyme. The reactants of the present invention are useful for chemical or biochemical measurement, detection or separation. Accordingly, the term xe2x80x9cReactantxe2x80x9d specifically excludes molecules, compounds, compositions or complexes, such as ink, that do not bind analytes as described above. Examples of reactants include, without limitation, amino acids, nucleic acids, including oligonucleotides and cDNA, carbohydrates, and proteins such as enzymes and antibodies.
xe2x80x9cRelaxation temperaturexe2x80x9d shall mean the temperature at which a heat-relaxable material exhibits a desired amount of relaxation.